West Nile Vaccine Still Several Years Away

September 7, 2003|By Justin Gillis The Washington Post

At least half a dozen laboratories and companies around the world are reporting headway in developing a vaccine against the West Nile virus, with enough tests completed in animals to suggest that several of the vaccines are likely to work in people. Two labs are expected to launch human tests by late this year.

Despite the rapid progress, an approved vaccine to prevent West Nile fever and its potentially life-threatening complications remains several years away, scientists said, because of the time needed to conduct thorough safety and effectiveness tests in people. And it remains unclear how large a commercial market a vaccine might command, given that the overwhelming majority of people infected with the virus never get sick.

Big vaccine companies have so far stayed away from West Nile virus, apparently deterred by the business uncertainties. But a handful of small biotechnology companies, motivated in part by government grants meant to prod industry into action, are chasing the goal of being first to market.

These companies see a potential market among older Americans, who appear to be at greatest risk of developing West Nile fever or its most severe complication, a potentially deadly swelling of the brain called encephalitis. And the companies are also betting that in the long run at least some American parents, weary of slathering their children with greasy insect repellent, will want a vaccine.

Many of the infectious diseases that have emerged in recent years have frustrated vaccinologists, most notably the human immunodeficiency virus, which causes AIDS. Almost 20 years of effort have produced no licensed vaccine. Likewise there is no vaccine for dengue fever, caused by a virus in the same family as West Nile. By contrast, West Nile virus, which was never seen in the Western Hemisphere and barely noticed by American medicine before a 1999 outbreak in New York, is defying the pattern. So far, every laboratory known to be working on a West Nile vaccine appears to be succeeding, a strong hint to scientists that such a vaccine will eventually be licensed.

When the 1999 outbreak began, the National Institute of Allergy and Infectious Diseases, a unit of the National Institutes of Health in Bethesda, Md., began pushing vaccine research and awarding grants. The costly initiative was controversial at the time, since it was unclear whether West Nile would become a lasting problem in North America. But now -- after thousands of cases throughout the United States, 284 deaths last year and 21 so far this year -- that early jump-start from NIH appears to have shaved years off the time that might have been needed to develop a vaccine.

It's unclear how widely such a vaccine would be used or whether authorities would recommend universal childhood vaccination. That will depend on how the epidemic unfolds over the next few years, said Anthony Fauci, director of the infectious-disease institute. In most people who get infected, the virus causes no symptoms and the person acquires strong immunity to West Nile. In a few cases, people get a fever. In a tiny minority, the disease turns into a life-threatening brain infection.

That has tended to happen in older people, which is why they might be the logical target for a vaccine, specialists said. But if the epidemic changes -- say, the virus starts making children ill -- that approach would likely change too.

"Would I see universal vaccination with West Nile at this point?" Fauci said. "Highly unlikely. But we need to go ahead and make the vaccine to plan for the worst."

Leading the pack is Acambis PLC, a company with headquarters in Cambridge, England, and U.S. operations in Cambridge, Mass. That company is best known for supplying the U.S. government with millions of fresh doses of smallpox vaccine that might be used to halt a bioterror attack, a set of contracts that propelled Acambis to prominence in the biotech industry -- and to early profitability by the standards of a biotech startup.

Acambis has already manufactured large amounts of a test vaccine for West Nile virus and will enter human trials within a few weeks, said Thomas Monath, the company's chief scientific officer. The company's product is a variant of the live virus used for decades to vaccinate people against yellow fever. It has been tweaked at a molecular level to look like West Nile on the outside, thus fooling the immune system into mounting a response that would be effective against later West Nile infection.

In trials, West Nile virus was injected directly into the brains of monkeys, the most rigorous animal test possible in a disease that causes brain inflammation. Monkeys that had not received the Acambis vaccine died, whereas monkeys that had received it lived, showing no sign of illness.